1. Field of the Invention
The present invention relates to an electrophoretic display device, and more particularly, to a color electrophoretic display device with a color filter layer, which is formed in a droplet state on a rear surface of an electronic ink film through surface treatment so as to be capable of adjusting density of droplets in pixels and achieving correct alignment, and a method for manufacturing the same.
2. Discussion of the Related Art
An electrophoretic display device (EPD) is one of flat panel display device used in E-books, and includes two display panels, on which electrodes for forming an electric field are formed, and micro capsules formed between the two display panels and containing electronic ink having black and white pigment particles respectively charged with positive and negative polarities.
The electrophoretic display device generates a potential difference at both ends of two electrodes opposite to each other by applying voltage to the two electrodes, and thus respectively moving the black and white pigment particles charged with positive and negative polarities to the electrodes having the opposite polarities, thereby displaying an image.
Such an electrophoretic display device has high reflectivity and contrast ratio and no dependence on a viewing angle, differing from a liquid crystal display device, and thus has advantages in that it displays an image in a comfortable mood like paper. Further, the electrophoretic display device has a bistable property between black and white, and thus maintains the image without continuous application of voltage, thereby reducing power consumption. Moreover, the electrophoretic display device does not require a polarization plate, an alignment film, and liquid crystals, and thus is advantageous in terms of price competitiveness.
The above electrophoretic display device and a color filter substrate disposed thereon form a color electrophoretic display device, which is capable of displaying colors.
Hereinafter, a conventional color electrophoretic display device will be described with reference to the accompanying drawings.
FIG. 1 is a longitudinal-sectional view illustrating the conventional color electrophoretic display device.
As shown in FIG. 1, the conventional color electrophoretic display device 100 usually includes a thin film transistor (TFT) array substrate 50, an electronic ink film 60, and a color filter substrate 70.
Here, the TFT array substrate 50 includes a first metal foil 12, such as steel use stainless (SUS) foil, formed on a glass substrate 10 to re-emit light emitted from the electronic ink film 60 toward an incident surface, and TFTs 13 formed on the first metal foil 12 to be driven according to respective pixels. The thin film transistor array substrate 50 further includes a second metal foil 14 formed on the rear surface of the glass substrate 10.
The electronic ink film 60 includes a micro capsule layer 25, which contains black and white pigment particles respectively charged with positive and negative polarities such that the black and white pigment particles are arranged in a designated direction through application of voltage thereto, formed on a transparent conductive film 20.
The color filter substrate 70 includes a first plastic film 32 formed on a glass substrate 30, and color filters 34 having designated colors formed in respective pixels on the first plastic film 32. The color filter substrate 70 further includes a second plastic film 31 for protection formed on the rear surface of the glass substrate 30.
Thereafter, a first adhesive layer 21 and a second adhesive layer 22 are respectively formed on the rear surface of the transparent conductive film 20 and on the micro capsule layer 25, and the color filter substrate 70 and the TFT array substrate 50 are respectively bonded to the electronic ink film 60 through the first adhesive layer 21 and the second adhesive layer 22, thereby forming the color electrophoretic display device 100.
In this case, in order to slim the device 100, after the bonding process, the glass substrate 30 and the second plastic film 31 of the color filter substrate 70 and the glass substrate 10 and the second metal foil 14 of the TFT array substrate 50 may be omitted.
However, in the conventional color electrophoretic display device 100 obtained by bonding the three panels, since the three panels are separately formed and then are bonded to each other by the bonding process carried out on both surfaces of the electronic ink film 60, a detaching process carried out, if misalignment among the three panels occurs, causes damage to the expensive electronic ink film 60, and thereby lowers image quality.
The above-described conventional color electrophoretic display device has several problems, as follows.
Since the conventional color electrophoretic display device is obtained by bonding the TFT array substrate and the color filter substrate to upper and lower surfaces of the electronic ink film through the respective adhesive layers, misalignment among the three panels may easily occur, and thereby causes damage to the expensive electronic ink film during re-working.
Subsequently, if misalignment remains, correct image display is not achieved, and if the electronic ink film is damaged, image quality at a damaged region is lowered.